A clean install might resolve the problem.
- Download the latest version of avast, 5.0.594
http://www.avast.com/free-antivirus-download and save it to your HDD, somewhere you can find it again (if you didn't save your last download). Use that when you reinstall.
- Download the avast! Uninstall Utility, aswClear5.exe
find it here and save it to your HDD (it has uninstall tools for both 4.8 and 5.0).
- 1. Now uninstall (using add remove programs, if you can't do that, no add remove entry, etc. start from the next step), reboot.
- 2. run the avast! Uninstall Utility from safe mode, first for 4.8 if previously installed and then for 5.0, once complete reboot into normal mode.
- 3. install the latest version, reboot.
It may be worth running some other scans first:
If you haven't already got this software (freeware), download, install, update and run it and report the findings (it should product a log file).
Don't worry about reported tracking cookies they are a minor issue and not one of security, allow SAS to deal with them though. - See
http://en.wikipedia.org/wiki/HTTP_cookie.
Also available a portable version of SAS,
http://www.superantispyware.com/portablescanner.html, no installation required.